Which of the following is a role of methyl groups in biochemistry?

Methyl groups play a significant role in influencing the shape and function of various biomolecules, particularly hormones. In the case of sex hormones, methylation can alter the three-dimensional structure of these molecules, which in turn affects their interactions with receptors and their biological activity. This structural modification can be crucial for ensuring that hormones like estrogen and testosterone perform their functions effectively in the body. Modifications such as methylation are essential in the regulation of gene expression and can impact numerous physiological processes.

The other options do not accurately represent the primary biochemical roles of methyl groups: enhancing photosynthesis pertains more to chlorophyll and light-capturing processes, energy production mainly involves metabolic pathways and ATP, and the formation of nucleic acids is primarily related to purines and pyrimidines rather than methyl groups.